A 17-page Al Qaida letter shows that Osama bin Laden has not been successful in recruiting Iraqis for the 'jihad' against the United States, raising questions about President George Bush's claim that Iraq is a recruiting ground for terrorists.

The letter, said ABC News quoting US military officials, appealed to Al Qaida leaders to help spark a civil war between Shias and Sunnis to 'tear the country apart'.

The letter is believed to have written by Jordanian Abu Musab al-Zarqawi. Al-Zarqawi is the chief suspect in several recent bombings, and the Bush administration cited his presence in Iraq as evidence of Iraq's terrorist connections even before the war.

Senior US officials termed the letter as proof that Al Qaida is active in Iraq. One officer quoted by ABC News warned the letter could mean more 'spectacular' attacks.

White House spokesman Scott McClellan said, "The letter shows that Iraq is the central front in the war on terrorism."

"There are foreign terrorists who realise the stakes are high and they seek to do everything they can to undermine the aspirations of the Iraqi people," McClellan said. "But democracy and freedom are taking root in Iraq and there's no turning back."

According to the New York Times the letter acknowledges problems in recruiting Iraqis to join the fight against an American force 'growing stronger day after day'.

"Many Iraqis would honour you as a guest and give you refuge, for you are a Muslim brother," it said. "However, they will not allow you to make their home a base for operations or a safe house."

The letter, many experts say, shows that Iraqis are willing to support an indigenous insurgency against the Americans, but do not want foreign militants to take root. Such a situation, they add, goes against what the American administration had been projecting all along -- Iraq as a haven for global terrorism.

The letter also raises the question whether Al Qaida had a network before the downfall of Saddam. Bush had repeatedly claimed before war that Al Qaida was turning Iraq into its base.

"There is little to bind Iraqi rebels to foreign terrorists other than a common wish to bloody the United States," former state department expert David L Phillips was quoted as saying in the NYT. Phillips is now with the Council on Foreign Relations.

"There are far more Iraqis who are resisting American occupation than there are al-Qaida operatives inside Iraq," he said. "Most violence against the U.S. in Iraq is being committed by so-called dead-enders and Iraqis who resent the US occupation."

Democrat Jane Harman of California, part of the House Intelligence Committee, told NYT that the Al Qaida is in Iraq because of the American presence in the country.

"It's a good organising tool," she said. "One of their big targets is America. There's a large American presence in Iraq."